Global Mission Parameters

Global mission parameters apply to the entire mission and all its mission tasks. However, whilst some parameter settings are inherited from the global configuration, certain mission task specific parameters can be configured independently and will override the global parameters during the execution of a mission task.

The global mission parameters can be accessed by clicking the mission name at the top of the Mission Planner pane to the left.

General

Mission Mode - There are two mission modes available — Subsonus Assisted and Standalone (GNSS / Dead Reckoning). The former mission mode requires a Subsonus whereas the latter allows for missions to be carried out with a standalone Hydrus unit. See Mission Modes for more information.

Name - Name of the mission plan. Allows for easy identification, reference and traceability.

Created - Mission plan creation date (system generated).

Modified - Mission plan last modified date (system generated).

Pause Vertical

Note: Pause vertical is only available in Subsonus Assisted Mission Mode.

The Pause Vertical parameter defines the vertical position to which the Hydrus descends at mission start. See Pause Vertical Position.

  • Vertical Mode - Determines the vertical reference point and method of measuring the vertical position during Pause Vertical.

  • Vertical - Distance in metres between the specified vertical mode reference and the Hydrus when starting the mission.

Travel

  • Travel Tilt - Specifies the travel tilt (pitch) of the Hydrus during travel between mission tasks.

    Travel tilt is a global mission parameter that determines the tilt of the Hydrus along the direction of travel and serves to enhance obstacle detection and altitude mode. As Hydrus moves forward, it utilises the DVL beam to look slightly ahead, aiding in obstacle detection and maintaining the appropriate altitude.

    When executing transect survey mission tasks, upon arrival at a designated picture-taking point, Hydrus adjusts its orientation to 0° or "look down" and captures the image. This enables it to obtain the desired visuals from a downward perspective.

    When executing lawnmower survey mission tasks, the Hydrus adjusts its orientation to the user specified pitch and captures the image.

    Note: Hydrus's travel tilt is limited to 30 degrees. This means that the camera angle can be adjusted within a range of -30 degrees to +30 degrees from the vertical position. Exceeding this limit may result in compromised data quality or operational issues. Exceeding 30 degrees of pose may result in loss of bottom tracking on the DVL, and reduce navigation performance.

Vertical

  • Vertical Mode - Determines the vertical reference point and method of measuring the vertical position during transits between mission tasks.

  • Vertical - Distance in metres between the specified vertical mode reference and the Hydrus when it is necessary for Hydrus to reacquire a navigation reference (DVL bottom lock) during the mission.

Capture

Default Capture Parameters - Global default camera settings. These settings will be inherited to all mission tasks unless they are overridden at mission task level. See Capture Parameters for details.

Media Overlay Parameters

Text overlays can be added to both images and video that are recorded during the mission. This is a global setting and applies to all mission tasks. The following metadata is recorded for both images and videos:

  • System time

  • User comment, if set by user

  • Mission name, if enabled

  • Heading

  • Latitude

  • Longitude

  • Depth / Altitude

  • Image Overlay Mode - Integrated Text Overlay - In this mode, a burned watermark with the above-listed is added to every photo.

  • Video Overlay Mode - If this parameter is set to Subtitle File (.vtt), data (time and location) recorded alongside with videos will be written to a vtt subtitle file. These subtitles are synchronised with the recorded footage and can easily be shown or hidden from the footage.

  • User Comment - Free text field that will be included in the media overlay, unless it is left empty.

  • Record Mission Name - When this setting is enabled, the mission name will be included in the media overlay.

Recovery Location

Home Point Type

  • Launch Location - In Standalone (GNSS/ Dead Reckoning) mission mode, this setting will instruct Hydrus to return to the same location from where it was deployed.

  • Geodetic Location - This home point type allows you to define the recovery location as geodetic coordinates (longitude and latitude).

  • Relative to Subsonus - In Subsonus Assisted mission mode, the recovery location can be specified as a Bearing and Distance of the Hydrus relative to the position of the Subsonus. If the position of the Subsonus changes during the mission, the recovery location will change accordingly.

When Reaching Recovery Location

  • Go to Surface - Hydrus will navigate to the recovery location and resurface directly. Hydrus will then utilise its thrusters to counteract any surface currents to remain in position.

  • Hold Position - Upon reaching the specified recovery location Hydrus will hold a vertical position as per the Vertical Mode and Vertical settings.

Vertical Mode

  • Bottom Altitude - This mode allows the user to set a height above the seafloor. Hydrus will maintain this altitude while following the lawnmower/transect pattern during the survey.

  • Surface Depth - This mode allows the user to define the depth of the Hydrus from the water surface. In this mode, the depth is measured in metres below the water surface. By setting a specific surface depth value, Hydrus will maintain a consistent depth below the water surface while following the survey path. This mode is useful when the focus is on capturing data at a specific depth level, such as conducting surveys near the water surface or targeting specific water layers.

  • Geodetic Height - This mode allows Hydrus to be set of a geodetic height, which is a measure of vertical distance above or below a specific geodetic reference point, such as the Earth's ellipsoid. By setting a specific geodetic height value, Hydrus can maintain a consistent altitude relative to the chosen reference datum throughout the survey. This mode is particularly useful when conducting surveys that require precise geospatial positioning and referencing, such as mapping, geodetic measurements, or integration with external geodetic datasets.

Note: Geodetic height only works in Subsonus Assisted mission mode and requires a GNSS fix from an external source e.g. a GNSS Compass.

Vertical - This setting determines the vertical position for the recovery location. It is define as a distance in metres between the Hydrus and the vertical reference point determined by the Vertical Mode setting.